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B F S E Y M 0 U R.

GEAR.

APPLICATION DEC-7,1917- 1,329,807. Patented Feb. 3,1920.

\\\\\\\\E1Ir um WM as rannr orrron BENJAMIN r. SEYMOUR, or DENVERLCOLORADO.

seen.

Specification of Letters latent. I Patented Feb. 3, 1920;

Original application filed. September 9, 1913, Serial No. 788,837. Divided and this application filed Decem- 1 her 7, 1917. Serial No. 205,933.

ticularlyto gears for use in change-speed.

transmissions, such as are used in automobile and machine-tool drives and the like.

This application is a division of Ser. No. 7 88,837 filed Sept. 9, 1913, and is for the purpose of protecting the novel geanper 86, which is described therein.

The gear, which constitutes the subject. matter of the present application, has a conlr cal pitch surface like a bevel gear but, un-;

like the latter, the teeth are of uniform thickness from front to rear, so that they can mesh with a spur gear the axis of which converges toward that of the gear. There-. fore,,a change-speed transmission may comprise-two or more ofqthe gears. of different diameters on one shaft and one driving pinion slidablv mounted on another shaft, the axis of which is parallel to the pitch cone of the gears. The pinioncan slide into mesh with each of the gears and out of mesh on the opposite side.

The essential feature of the new gear is that. While the teeth are cut on a conical blank, their sides do not converge, as do the sides of the teeth of bevel gears, but are parallel. that is, a linear element on one side of a tooth is parallehthroughout the length of the tooth to the-corresponding linear element on the other side of the tooth, the corresponding ends of said elements being at the same distances from the axis of the gear.

The invention is illustrated in its preferred form in the accompanying drawing,

drive comprising three of the new gears and one driving spur pinion.

Fig.

I with the pinion, and,

Fig. 3 is an enlargedfragmentary view of the gear.

1 represents the shaft on which the pinion 3 is slidablv keved. and 2 the convergent shaft on which the ears 4. 5 and 6 are fixed. As shown. the teeth 7 of the pinion are ordinary involute teeth, which form "is the 2 is a front elevation of a gear in mesh best suited for the purposes of my invention.

The teeth 8 of the gear. are cut, as stated, in a blank the perimeter of which is a cone, the apex angle of which, when the gear is to mesh with a spur pinion, is equal to twice the angle between the axes of the two shafts. The gear teeth must of course be conjugate to those of the pinion that is, in the present case, must be involute teeth. For conventhe shape of involute rack teeth. which is that of a truncated triangle. The preferred form is that illustrated in the drawing, and is given to the teeth by first cutting inverted truncated V shaped grooves and then taking-a secondcut with the same tool traveling at an angle to its path in the first cut so as to progressively remove metal from the sides of the teeth from the front '65 ience in cutting them they may be made of to therear, leaving the teeth of equal thick-= ness throughout. A cut is then taken with a concave nosed tool starting from the front corner of the truncated V and progressively removing metal from the working face so as to round it 0E in a curve like that of an involute gear tooth at' the rear. A

slight sliding contact takes place between the teeth of the pinion and those of the gear at this point, that is. toward the rear end of the gear teeth where theyv are rounded off, before the true rolling contact com men'ces, this being necessitated by the fact that the sides of thesnaces between the gear teeth diverge toward the rear while the sidesof t e spaces between the pinion teeth are parallel." I H i Wh t I claim is:. f

1. The combination with two shafts the .axesof which are converr ent. of conjugate toothed gears thereon adapted to be slid into and out of mesh with each other from either direction. the workinrr faces of the teeth of one of said nears being'redu ed in thickness pro ressively throughout their length from front to rear.

2. A conical gear adapted to mesh with a spur gear. the teeth of said conical gear having at th ir front ends the shape of an involute rack tooth'and at their rear ends the shape of an involute ear tooth.

3. A conical near a apted to slide into and out of mesh in either direction with a coniugate .q-earohavinrr its axis at an angle ,to'the axis'of said conical gear, the teeth 2 to 5 M 7 0f the l ttei' being of thoshafie ofinvohlt in' any conioal su rface concehtri with the rack teeth with their working faces propitch surface, and having its said Working 'gressively rounded off from front to rear. faces progressively reduced in thickness from 10" 4. A1 conicalgear adapted to mesh with front to rear.

5 a'ispui gear and having each tooth of siib- In testimony whereof I'hml o hereiinto set I ,sta tially uniform thlckness between its my hand. jworking faces from front to rear measured BENJAMIN SEYMOUR; 

